From d38911f1a9d7f0ec39a74a95994d95291f1922c3 Mon Sep 17 00:00:00 2001
From: Marcus Pettersen Irgens <m@mrcus.dev>
Date: Thu, 5 May 2022 22:59:51 +0200
Subject: [PATCH] Allow absolute URLs to the GraphQL playground (#2142)

* Allow absolute URLs to the GraphQL playground

* Add test for playground URLs

* Close res.Body in playground test
---
 graphql/playground/playground.go      | 52 ++++++++++++++++++++-----
 graphql/playground/playground_test.go | 56 +++++++++++++++++++++++++++
 2 files changed, 98 insertions(+), 10 deletions(-)
 create mode 100644 graphql/playground/playground_test.go
diff --git a/graphql/playground/playground.go b/graphql/playground/playground.go
index 52f9305b3fe..ce7bf027881 100644
--- a/graphql/playground/playground.go
+++ b/graphql/playground/playground.go
@@ -3,6 +3,7 @@ package playground
 import (
 	"html/template"
 	"net/http"
+	"net/url"
 )
 
 var page = template.Must(template.New("graphiql").Parse(`<!DOCTYPE html>
@@ -36,9 +37,14 @@ var page = template.Must(template.New("graphiql").Parse(`<!DOCTYPE html>
 	></script>
 
     <script>
-      const url = location.protocol + '//' + location.host + '{{.endpoint}}';
+{{- if .endpointIsAbsolute}}
+      const url = {{.endpoint}};
+      const subscriptionUrl = {{.subscriptionEndpoint}};
+{{- else}}
+      const url = location.protocol + '//' + location.host + {{.endpoint}};
       const wsProto = location.protocol == 'https:' ? 'wss:' : 'ws:';
-      const subscriptionUrl = wsProto + '//' + location.host + '{{.endpoint}}';
+      const subscriptionUrl = wsProto + '//' + location.host + '/foo';
+{{- end}}
 
       const fetcher = GraphiQL.createFetcher({ url, subscriptionUrl });
       ReactDOM.render(
@@ -59,17 +65,43 @@ var page = template.Must(template.New("graphiql").Parse(`<!DOCTYPE html>
 func Handler(title string, endpoint string) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Add("Content-Type", "text/html")
-		err := page.Execute(w, map[string]string{
-			"title":       title,
-			"endpoint":    endpoint,
-			"version":     "1.8.2",
-			"cssSRI":      "sha256-CDHiHbYkDSUc3+DS2TU89I9e2W3sJRUOqSmp7JC+LBw=",
-			"jsSRI":       "sha256-X8vqrqZ6Rvvoq4tvRVM3LoMZCQH8jwW92tnX0iPiHPc=",
-			"reactSRI":    "sha256-Ipu/TQ50iCCVZBUsZyNJfxrDk0E2yhaEIz0vqI+kFG8=",
-			"reactDOMSRI": "sha256-nbMykgB6tsOFJ7OdVmPpdqMFVk4ZsqWocT6issAPUF0=",
+		err := page.Execute(w, map[string]interface{}{
+			"title":                title,
+			"endpoint":             endpoint,
+			"endpointIsAbsolute":   endpointHasScheme(endpoint),
+			"subscriptionEndpoint": getSubscriptionEndpoint(endpoint),
+			"version":              "1.8.2",
+			"cssSRI":               "sha256-CDHiHbYkDSUc3+DS2TU89I9e2W3sJRUOqSmp7JC+LBw=",
+			"jsSRI":                "sha256-X8vqrqZ6Rvvoq4tvRVM3LoMZCQH8jwW92tnX0iPiHPc=",
+			"reactSRI":             "sha256-Ipu/TQ50iCCVZBUsZyNJfxrDk0E2yhaEIz0vqI+kFG8=",
+			"reactDOMSRI":          "sha256-nbMykgB6tsOFJ7OdVmPpdqMFVk4ZsqWocT6issAPUF0=",
 		})
 		if err != nil {
 			panic(err)
 		}
 	}
 }
+
+// endpointHasScheme checks if the endpoint has a scheme.
+func endpointHasScheme(endpoint string) bool {
+	u, err := url.Parse(endpoint)
+	return err == nil && u.Scheme != ""
+}
+
+// getSubscriptionEndpoint returns the subscription endpoint for the given
+// endpoint if it is parsable as a URL, or an empty string.
+func getSubscriptionEndpoint(endpoint string) string {
+	u, err := url.Parse(endpoint)
+	if err != nil {
+		return ""
+	}
+
+	switch u.Scheme {
+	case "https":
+		u.Scheme = "wss"
+	default:
+		u.Scheme = "ws"
+	}
+
+	return u.String()
+}
diff --git a/graphql/playground/playground_test.go b/graphql/playground/playground_test.go
new file mode 100644
index 00000000000..7d2b081f7df
--- /dev/null
+++ b/graphql/playground/playground_test.go
@@ -0,0 +1,56 @@
+package playground
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"regexp"
+	"testing"
+)
+
+func TestHandler_createsAbsoluteURLs(t *testing.T) {
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "https://example.org/query", nil)
+	h := Handler("example.org API", "https://example.org/query")
+	h.ServeHTTP(rec, req)
+
+	res := rec.Result()
+	defer res.Body.Close()
+	if res.StatusCode != http.StatusOK {
+		t.Errorf("res.StatusCode = %d; want %d", res.StatusCode, http.StatusOK)
+	}
+
+	b, err := io.ReadAll(res.Body)
+	if err != nil {
+		panic(fmt.Errorf("reading res.Body: %w", err))
+	}
+
+	want := regexp.MustCompile(`(?m)^.*url\s*=\s*['"]https:\/\/example\.org\/query["'].*$`)
+	if !want.Match(b) {
+		t.Errorf("no match for %s in response body", want.String())
+	}
+}
+
+func TestHandler_createsRelativeURLs(t *testing.T) {
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "http://localhost:8080/query", nil)
+	h := Handler("example.org API", "/query")
+	h.ServeHTTP(rec, req)
+
+	res := rec.Result()
+	defer res.Body.Close()
+	if res.StatusCode != http.StatusOK {
+		t.Errorf("res.StatusCode = %d; want %d", res.StatusCode, http.StatusOK)
+	}
+
+	b, err := io.ReadAll(res.Body)
+	if err != nil {
+		panic(fmt.Errorf("reading res.Body: %w", err))
+	}
+
+	want := regexp.MustCompile(`(?m)^.*url\s*=\s*location.protocol.*$`)
+	if !want.Match(b) {
+		t.Errorf("no match for %s in response body", want.String())
+	}
+}
